|Sounds like the drive may be dead, making any data recovery an expensive endeavor.|
But to make sure it's interferring with the good drive on the same data cable, connect the possibly bad drive by itself on the secondary IDE port. (You may need to temporarily disconnect whatever is on that cable--cdrom, etc.) That is, assuming the other PC has both primary and secondary ports.
Another thing, are you sure the 'other computer' is able to see the drive OK? Big drives attached to old motherboards sometimes aren't seen right.
Help me Jebus!